Beschrijving:The flight departed Minneapolis, Minnesota, at 07:46, on February 27, 1951, for Houston, Texas, via scheduled intermediate points. During the flight the left engine torque meter pressure indication was approximately 90 FSI, the normal being approximately 145 PSI. The flight departed Kansas City and proceeded in a routine manner to Tulsa, arriving at 12:44. The left engine, torque meter pressure indicator was considered inoperative because of its low reading, and was, therefore, disregarded during the flight. Following touchdown at Tulsa, the propellers were placed in reverse thrust, and when being returned to positive thrust, the left propeller went to the full feathered position and the engine ceased operation. While taxiing to the loading ramp, attempts were made to start the left engine but were not successful. On departure from Tulsa, no difficulty was encountered in starting the left engine, and the propeller which was in the full feathered position was returned to the low pitch position by use of the propeller governor control. Takeoff was accomplished from Tulsa at 13:02. Prior to takeoff, the engines were run up and the pre-flight check accomplished using a check list. All items checked satisfactorily, with the exception that the left engine torque meter pressure indicator was abnormally low. Flaps were positioned at 24 degrees for takeoff. The take-of roll was started on runway 12 and the aircraft became airborne at 124 mph, or slightly higher. The landing gear was immediately retracted and the airspeed was then observed to be 145 mph at this time, at an altitude estimated to be not over 50 feet, the left propeller was observed to feather and then immediately to rotate slowly. It continued to rotate until the aircraft struck the ground. The crew first became aware that the left engine was malfunctioning when a severe vibration was felt immediately after the gear had been retracted and at the same time the aircraft yawed to the left momentarily. Both engine controls were left at the takeoff setting, and a single-engine climb was then initiated. The airspeed decreased to approximately 124 mph during the climb to a maximum altitude of approximately 150 feet. At this point the aircraft was leveled off and a shallow turn to the left was made to avoid flying over a building. As the aircraft started turning at an approximate air speed of 122 miles per hour, the flaps were retracted from the 24-degree position to the 12-degree position. While in the left turn, the aircraft lost altitude steadily until it struck a grove of trees at a point approximately 17 feet above the ground. After striking the trees it slid on the ground on the underside of the fuselage. All passengers and crew were evacuated safely and in an orderly manner. The aircraft was destroyed by fire.

Probable Cause:

PROBABLE CAUSE: "The retraction of the flaps from the takeoff setting at a critical air speed, following the failure of the left engine torque meter assembly."

This information is not presented as the Flight Safety Foundation or the Aviation Safety Networkís opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.